tRNAPhe cleavage by aminoglycosides is triggered off by formation of an abasic site

This communication reports the characteristics of the mechanism of highly specific tRNA(Phe) cleavage, which occurs in the anticodon loop in the presence of aminoglycoside antibiotic-neomycin B. The data prove that the cleavage requires previous depurination of the polynucleotide chain at position 37, which is occupied by a hypermodified guanine base-wybutine. The results suggest that the phenomenon, previously considered as selective with respect to the presence of tRNA hypermodification, may concern far more RNA molecules, namely the ones carrying abasic sites.     

Gynecomasty as a first sign of adrenal carcinoma--case report

We present a case of 50 year-old man with feminizing adrenal carcinoma. He was admitted to the hospital because of weakness and one year history of gynecomastia and high blood pressure. Examinations revealed a large left adrenal mass and increased levels of estradiol. Patient underwent adrenalectomy and followed by mitotan therapy as the result of histopathological examination was adrenocortical carcinoma. One year after operation patient stays free from the recurrence of the disease and his estradiol, androstendion and DHEA levels are below the detection limits. We report this case because feminizing adrenal carcinoma is a very rare but serious disease and gynecomastia that could be its manifestation is quite frequent symptom in men's population and thus it could easily be missed. In every case of gynecomastia related to estradiol excess feminizing tumors of testis and adrenal gland should be ruled out.     

Positive effects of DHEA therapy on insulin resistance and lipids in men with angiographically verified coronary heart disease--preliminary study

OBJECTIVES: The aim of this study was to analyze the influence of DHEA therapy on insulin resistance (FIRI, FG/FI) and serum lipids in men with angiographically verified coronary heart disease (CHD). MATERIAL AND METHODS: The study included thirty men aged 41-60 years (mean age 52+/-0.90 yr) with serum DHEA-S concentration<2000 microg/l, who were randomized into a double-blind, placebo-controlled, cross-over trial. Subjects completed the 80 days study of 40 days of 150 mg oral DHEA daily or placebo, and next groups were changed after 30 days of wash-out. Fasting early morning blood samples were obtained at baseline and after each treatment to determine serum hormones levels (testosterone, DHEA-S, LH, FSH estradiol and IGF-1) and also metabolic profile (total cholesterol, LDL-cholesterol, triglicerides, HDL-cholesterol, insulin, glucose, fasting insulin resistance index--FIRI and FG/FI ratio). RESULTS: Administration of DHEA was associated with 4.5-fold increase in DHEA-S levels. Relative to baseline DHEA administration resulted in a decrease in insulin levels by 40% (p<0.005) and fasting insulin resistance index (FIRI) by 47% (p<0.004). Also total cholesterol levels and LDL-cholesterol levels decreased significantly (from 222.9+/-6.6 mg/dL to 207.4+/-6.6 mg/dL and from 143.9+/-6.9 mg/dL to 130.5+/-6.0 mg/dL respectively; p<0.05). Glucose levels dropped significant below baseline values after DHEA (p<0.001). Estrogen levels significantly increased after DHEA (p<0.05). While changes of serum concentrations of testosterone, LH, FSH, IGF-I, HDL-cholesterol, triglycerides were not statistical significant. Tolerance of the treatment was good and no adverse effects were observed. CONCLUSIONS: DHEA therapy in dose of 150 mg daily during 40 days in men with DHEA levels<2000 microg/l decreased total cholesterol concentration, insulin and glucose levels and fasting insulin resistance index (FIRI). This therapy may be a beneficial against CHD risk factors.     

Macroprolactin in subjects with hyperprolactinaemia: clinical observations and relations between free PRL and PRL complexed with IgG

In some patients with hyperprolactinaemia a large portion of circulating prolactin is bound to authologous gammaglobulin and therefore it is called macroprolactin or Big-Big-Prolactin (BB-PRL). THE AIM: of the study was to select patients with predominance of macroprolactin and to learn more about the natural course of this disorder, in particular about the possible dependence of the presence of clinical features from the amount of circulating "free" PRL level, and also to search whether the quantitative proportions of both forms of PRL are stable or they change parallel to changes of the total serum PRL level. MATERIAL AND METHODS: We identified 58 patients with hyperprolactinaemia, in whom BB-PRL consisted>or=60% of the total PRL concentration. The predominance of macroprolactin was settled using the well accepted method of polyethylene glycol (PEG) precipitation of large m.w. serum proteins, followed by contemporary immunoradiometric measurement of the total and free PRL levels, and calculation of BB-PRL. Repeating such measurements during the long term observation lasting 6-66 months (mean 33 months), which was possible in 18 our patients (13--with idiopathic hyperprolactinaemia and 5--with pituitary adenoma), we could analyze the relations between both forms of PRL during the specific treatment, after it's cessation and, in few cases--during pregnancy. Apart of that, in 18 patients selected from 53 with idiopathic hyperprolactinaemia, we analyzed the shortterm alterations in the ratio between free and complexed PRL during the metoclopramide PRL stimulation test. RESULTS AND CONCLUSIONS: 1. In hyperprolactinaemic patients with predominance of BB-PRL, there was no direct correlation between the presence of clinical features and the concentration of residual "free" PRL. 2. During the long-term observation, in spite of moderate changes in the total PRL concentration induced by the treatment or it's cessation (excluding pregnancy), the ratio of "free" PRL and BB-PRL remained stable. 3. During the short time of metoclopramide stimulation test, there was a marked rise mainly of the total and "free" PRL concentrations, and, in some tested subjects, the predominance of BB-PRL was lost temporally for 1 to 2 hours.     

The relationship between testosterone and dehydroepiandrosterone sulfate concentrations, insulin resistance and visceral obesity in elderly men

INTRODUCTION: Sex hormones deficiency--hypotestosteronemia (20-30% of men) and dehydroepian-drosterone sulfate deficiency (60-70% of men) are often observed in elderly men. In these men also changes of body composition (visceral obesity, increasing of fat mass), and metabolic disturbances (hypercholesterolemia, hyperinsulinism and insulin resistance) are common disorders. Visceral obesity and insulin resistance may be either reasons or effects of testosterone deficiency. Probably also DHEA-S deficiency is the risk factor of visceral obesity and insulin resistance, but it is not clear, whether this possible influence is independent from testosterone deficiency. OBJECTIVES: The aim of this study was to analyze the association between testosterone and DHEA deficiency and waist/hip ratio (WHR), levels of glucose and insulin resistance (HOMA and FG/FI) in elderly men as well as analysis, whether these sex hormones influent on measured parameters separately. MATERIAL AND METHODS: Together 85 men with age from 60 to 70 years men (mean 66.3+/-1.5 years; mean+/-SEM) was analyzed. Testosterone levels<4 ng/ml or DHEA levels<2000 ng/ml and BMI<30 kg/m2 were including criteria. Patients were divided into three groups: 52 with testosterone deficiency (L-T), 32 with DHEA deficiency (L-DHEA-S) and 67 with deficiency of both sex hormones (L-T/DHEA-S). Statistical analysis was made using Student-t, Kruskal-Wallis, and Mann-Whitney tests. RESULTS: Testosterone levels in L-T, L-DHEA and L-T/DHEA groups were respectively 3.19+/-0.23 ng/ml, 4.89+/-0.45 ng/ml and 3.25+/-0.34 g/ml (p<0.002). While DHEA-S levels were respectively 2498+/-98 ng/ml, 1435+/-1010 ng/ml and 1501+/-89 ng/ml). BMI values do not differ between groups. WHR ratio values were the highest in L-T/DHEA-S group (p<0.05 vs. L-T) group, significant lower in L-T group (p<0.005 vs. L-DHEA-S) and the lowest in L-DHEA-S group. Insulin fasting levels were lowest in L-DHEA-S group, higher in L-T group (p<0.01) and the highest in L-T/DHEA-S group (p<0.001 vs, L-T group). FG/FI values were the highest in L-DHEA-S group, lower in L-T group (NS) and lowest in L-T/DHEA group (p<0.002 vs. L-T group). HOMA ratio values similarly did not change significantly between L-T (6.6+/-3.21) and L-DHEA-S group (5.5+/-2.92), although tendency to higher values in L-T group was noticed, while WHR ratio values were significantly higher in L-T/DHEA group (7.3+/-2.45; p<0.002 vs. L-T group). CONCLUSIONS: DHEA-S and testosterone deficiency were independently associated with higher insulin resistance and obesity. WHR ratio seems to be more sensitive then BMI ratio to reflect the androgen deficiency on obesity and body composition in elderly men.     

Inhibition of prolidase activity by nickel causes decreased growth of proline auxotrophic CHO cells

Occupational exposure to nickel has been epidemiologically linked to increased cancer risk in the respiratory tract. Nickel-induced cell transformation is associated with both genotoxic and epigenetic mechanisms that are poorly understood. Prolidase [E.C.3.4.13.9] is a cytosolic Mn(II)-activated metalloproteinase that specifically hydrolyzes imidodipeptides with C-terminal proline or hydroxyproline and plays an important role in the recycling of proline for protein synthesis and cell growth. Prolidase also provides free proline as substrate for proline oxidase, whose gene is activated by p53 during apoptosis. The inhibition of prolidase activity by nickel has not yet been studied. We first showed that Ni(II) chloride specifically inhibited prolidase activity in CHO-K1 cells in situ. This interpretation was possible because CHO-K1 cells are proline auxotrophs requiring added free proline or proline released from added Gly-Pro by prolidase. In a dose-dependent fashion, Ni(II) inhibited growth on Gly-Pro but did not inhibit growth on proline, thereby showing inhibition of prolidase in situ in the absence of nonspecific toxicity. Studies using cell-free extracts showed that Ni(II) inhibited prolidase activity when present during prolidase activation with Mn(II) or during incubation with Gly-Pro. In kinetic studies, we found that Ni(II) inhibition of prolidase varied with respect to Mn(II) concentration. Analysis of these data suggested that increasing concentrations of Mn(II) stabilized the enzyme protein against Ni(II) inhibition. Because prolidase is an important enzyme in collagen metabolism, inhibition of the enzyme activity by nickel could alter the metabolism of collagen and other matrix proteins, and thereby alter cell-matrix and cell-cell interactions involved in gene expression, genomic stability, cellular differentiation, and cell proliferation.     

Antibacterial and antifungal lysozyme-type activity in Cameraria ohridella pupae

Lysozyme-type antibacterial and antifungal activity in pupae of Cameraria ohridella was studied. Activity against Micrococcus luteus and Bacillus megaterium was detected in pupae extract. Also antifungal activity from C. ohridella pupae extract directed against Saccharomyces cerevisiae strain W 303 was shown. During immunoblotting two bands in pupae extract, with molecular mass of about 15 and 28 kDa were recognized by antibodies directed against HEWL. After acid electrophoresis followed by bioautography of the extract, two lytic zones showing lysozyme-type activity against M. luteus were observed. Two bacteria: Gram-positive Aerococcus viridans and Gram-negative Aeromonas salmonicida ssp. masoucida were isolated from pupae of C. ohridella. Their activity against M. luteus, B. megaterium, and S. cerevisiae W303 was detected. After immunoblotting with antibodies against HEWL, also two proteins from bacterial suspensions of A. viridans and A. salmonicida were detected, about 15 and 28 kDa.     

Uracil misincorporation into DNA of leukocytes of young women with positive folate balance depends on plasma vitamin B12 concentrations and methylenetetrahydrofolate reductase polymorphisms. A pilot study

Changes in the folate and vitamin B12 status in the body influence the extent of uracil misincorporation (UrMis) into DNA, which is one of the biomarkers of genomic stability and, thus, portends a risk of cancer. In our study, the level of UrMis into DNA was evaluated by the comet assay (using the specific DNA repair enzyme, uracil DNA glycosylase) in leukocytes from blood donated by healthy young women with positive folate balance achieved by 4 weeks of folic acid supplementation (400 microg/day). The nutritional status was evaluated on the basis of nine food diaries recorded by the subjects during two winter months. The data were computerized, and the intake of nutrients and micronutrients was estimated using the DIETA 2 program (Food and Nutrition Institute, Warsaw, Poland) linked to recently updated Polish food tables. The plasma folate and vitamin B12 concentration, as well as methylenetetrahydrofolate reductase (MTHFR) polymorphisms, were evaluated to determine their influence on the level of UrMis into DNA. The mean value of B12 intake for all subjects reached 100% of the Polish recommended dietary allowances (RDA), whereas the mean value of folate intake, before folate supplementation, was 50%, suggesting moderate deficiency. Folic acid supplementation brought the folate intake way above the RDA, and plasma folate concentration in each individual was above the deficient range (mean value 14.67 ng/ml). The UrMis did not correlate with the plasma folate concentration, but the level of UrMis was significantly lower in subjects with plasma vitamin B12 concentration above 400 pg/ml (P=.02) only after folic acid supplementation. The concentration of folate in plasma correlated (P相似文献   

Mutator phenotype resulting from DNA polymerase IV overproduction in Escherichia coli: preferential mutagenesis on the lagging strand

We investigated the mutator effect resulting from overproduction of Escherichia coli DNA polymerase IV. Using lac mutational targets in the two possible orientations on the chromosome, we observed preferential mutagenesis during lagging strand synthesis. The mutator activity likely results from extension of mismatches produced by polymerase III holoenzyme.